07-02-2011, 09:30 AM
If you are receiving stations strongly but at the wrong place on the dial, you'll need to do a full alignment to calibrate the oscillator to the dial. If you have a signal generator alignment is not difficult on that radio. I've done a couple of them.
If you don't have a signal generator you can do the AM dial alignment using AM stations near 1500 Hz and 580 Hz if you know their actual frequency, but you won't be able to align the IF cans properly. Do you have alignment instructions from Philco or Rider? Short wave dial alignment will be a problem unless you can find a station near 15 MHz, that you know the actual frequency of. WWV broadcasts at 15 MHz exactly if you can pick that station up.
You can approximate the IF alignment if you use a weak station and be sure you adjust the IF cans in the order 55A, 42C, 33B, 33A. The IF alignment will be approximate and performance will probably suffer, but it is better than nothing.
To get the dial alignment correct you will need to connect the loop antenna. If you have a wire antenna at your workbench for test purposes like I do, don't use it for the dial alignment because the alignment will change when you put the chassis back in the cabinet. On most radios it is hard to reach the compensators with the chassis installed in the cabinet. The way I do it is to put the chassis and the cabinet on the bench back-to-back so you can connect the loop antenna while still being able to reach the compensators from above. This method isn't perfect, but it is the only way I've figured out to do a pretty good dial alignment with the loop connected as it should be. If anyone has other suggestions how to do this I'd sure like to hear them.
I've tried the FM alignment per the Philco instructions, but it doesn't matter much since there aren't any FM stations down at the old pre-war band. If I want to listen to FM on my pre-war radios I run the audio from an FM tuner through my AM transmitter and just use the AM band to tune in my transmitter.
I don't know why, but I am sometimes able to get strong modern FM stations and TV sound from my pre-war FM radios. The sound is low fidelity and faint. I figure it may have to do with harmonics of the FM IF frequency, but I don't really understand it.
If you don't have a signal generator you can do the AM dial alignment using AM stations near 1500 Hz and 580 Hz if you know their actual frequency, but you won't be able to align the IF cans properly. Do you have alignment instructions from Philco or Rider? Short wave dial alignment will be a problem unless you can find a station near 15 MHz, that you know the actual frequency of. WWV broadcasts at 15 MHz exactly if you can pick that station up.
You can approximate the IF alignment if you use a weak station and be sure you adjust the IF cans in the order 55A, 42C, 33B, 33A. The IF alignment will be approximate and performance will probably suffer, but it is better than nothing.
To get the dial alignment correct you will need to connect the loop antenna. If you have a wire antenna at your workbench for test purposes like I do, don't use it for the dial alignment because the alignment will change when you put the chassis back in the cabinet. On most radios it is hard to reach the compensators with the chassis installed in the cabinet. The way I do it is to put the chassis and the cabinet on the bench back-to-back so you can connect the loop antenna while still being able to reach the compensators from above. This method isn't perfect, but it is the only way I've figured out to do a pretty good dial alignment with the loop connected as it should be. If anyone has other suggestions how to do this I'd sure like to hear them.
I've tried the FM alignment per the Philco instructions, but it doesn't matter much since there aren't any FM stations down at the old pre-war band. If I want to listen to FM on my pre-war radios I run the audio from an FM tuner through my AM transmitter and just use the AM band to tune in my transmitter.
I don't know why, but I am sometimes able to get strong modern FM stations and TV sound from my pre-war FM radios. The sound is low fidelity and faint. I figure it may have to do with harmonics of the FM IF frequency, but I don't really understand it.
John Honeycutt
